The effects of transmural nerve stimulation induced releasing neurotransmitters on the changes of swine uterine smooth muscle motility were examined by polygraph through isometric force transducer. The frequency dependent relaxation and rebound contraction were revealed on precontraction with histamine by transmural nerve stimulation. The rebound contraction by transmural nerve stimulation was inhibited by nonselective ${alpha}$-adrenergic receptor antagonist, phentolamine, and the relaxation by transmural nerve stimulation was blocked by nonselective ${eta}$-adrenergic receptor antagonist, propranolol. The relaxation induced by nonselective ${eta}$-adrenergic receptor agonist, isoproterenol on precontraction with histamine were the dose dependent manner and this relaxation was blocked by nonselective ${eta}$-adrenergic receptor antagonist, propranolol in isolated uterine smooth muscle of pig. These results suggest that endogenous neurotransmitters on smooth muscle relaxation was influenced by ${eta}$-adrenergic receptor in swine.